For more information on interface scaling, see the Fabric Engine Release Notes.
The software does not support virtualized PIM. PIM is supported in the Global Routing Table only.
Interfaces that run PIM must also use a unicast routing protocol (PIM uses the unicast routing table), which puts stringent requirements on the system. With a high number of interfaces, take special care to reduce the load on the system.
Use few active IP routed interfaces. You can use IP forwarding without a routing protocol enabled on the interfaces, and enable only one or two with a routing protocol. You can configure proper routing by using IP routing policies to announce and accept routes on the switch. Use PIM passive interfaces on the majority of interfaces.
Important
For information on the maximum values for total PIM interfaces and active interfaces, see the Fabric Engine Release Notes. If you configure the maximum number of active interfaces, all remaining interfaces must be passive.
When you use PIM-SM, the number of routes can scale up to the unicast route limit because PIM uses the unicast routing table to make forwarding decisions. For higher route scaling, use OSPF instead of Routing Information Protocol (RIP).
As a general rule, a well-designed network does not have many routes in the routing table. For PIM to work properly, ensure that all subnets configured with PIM are reachable and that PIM uses the information in the unicast routing table. For the RPF check, to correctly reach the source of any multicast traffic, PIM requires the unicast routing table.